The present invention relates generally to test and diagnosis equipment for testing electrical circuits of engine-powered vehicles, particularly vehicles powered by internal combustion engines. The invention has particular application to small engine-powered vehicles, including small lawn and garden vehicles, such as tractors, lawn mowers and the like.
Many small motor vehicles, such as, tractors, riding or push-type lawn mowers, or similar lawn and garden vehicles, are powered by internal combustion engines and are provided with on-board electrical circuits which control and monitor many operations of the engine and other aspects of the vehicle. Such on-board circuits may control such things as engine starting and ignition, lighting, displays and various safety interlocks. For example, in a typical tractor lawn mower there are "dead man" interlocks which prevent the engine from starting or the mower blade or the propulsion wheels of the vehicle from being engaged unless the operator is seated on the vehicle seat, with his foot on the brake. In this regard, such vehicles are typically provided with an ignition keyswitch similar to that in an automobile, which may have multiple positions, such as LOCK or OFF, ON and START. Such vehicles are also commonly provided with a number of indicators, such as indicator lights or the like, which are designed to be energized in various keyswitch positions, to indicate the condition of the vehicle to the operator. Thus, when the keyswitch is turned ON, various indicator lamps may light to indicate the condition of certain systems of the vehicle, and may indicate whether or not it is safe to start the vehicle.
Heretofore testing of the electrical circuits of such vehicles has been a time-consuming process. Typically, test equipment such as a voltmeter, ammeter or the like has been utilized to manually test the voltage or current condition at various points in the circuitry. It could, with certain vehicles, take up to 45 minutes to complete a test procedure necessary to isolate and identify a circuit fault.